Various types of video and electronic content present content that changes over time. Video, for example, typically consists of a series of frames that are played or otherwise displayed one after another. People, animals, automobiles, buildings, background, and other objects can appear on multiple frames of a video. For example, a person may appear to walk along a street from one side of a video to the other over the course of the video. More specifically, in the first frame of the video, the person may appear in a position at the far left of the displayed content, in the next frame the person may appear slightly to the right of its position in the prior frame, etc. Generally, the person may appear different in the various frames of the video. For example, as the person walks, the person's arms may swing back and forth and the person's body orientation may change.
Video editing environments allow video to be edited in various ways. Video editing environments, for example, may allow the addition of a border, title, animation, or other new object to a video. However, to add such objects in multiple frames of a video, a developer may be required to work with the individual frames of the video. For example, if a developer wishes to add a speech bubble that moves with a person in a video, the developer may have to reposition the speech bubble in each frame of the video as the person moves around. Alternatively, in a video editing environment, movement of an added object may be associated with the movement of one of the video's objects. However, such automation may result in excessive computation and undesirable movement of the added object. For example, the movement of the added object may not appear smooth. Generally, improved techniques for creating and using moving objects in video and similar electronic content are needed.